package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 * @author 刘宇
 */
@Component
public class RedisIdWorker {
    /**
     * 开始时间戳
     */
    private static final long BEGIN_TIMESTAMP = 1704067200L;
    /**
     * 序列号的位数
     */
    private static final long COUNT_BITS = 32;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    //根据前缀生成订单id
    public Long nextId(String keyPrefix){
        //1.生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long nowSeconds=now.toEpochSecond(ZoneOffset.UTC);
        long timestamp=nowSeconds-BEGIN_TIMESTAMP;
        //2.生成序列号
        //2.1获取当前日期 精确到天 好处:1.避免超过32位的key 2.方便统计
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        //2.2自增长
        long count = stringRedisTemplate.opsForValue().increment("icr:"+keyPrefix+":"+date);
        //3.拼接并返回
        return timestamp<<COUNT_BITS|count;
    }
}
